ME325 EXAM I (Sample)

Transcription

1 ME35 EXAM I (Sample) NAME: NOTE: COSED BOOK, COSED NOTES. ONY A SINGE 8.5x" ORMUA SHEET IS AOWED. ADDITIONA INORMATION IS AVAIABE ON THE AST PAGE O THIS EXAM. DO YOUR WORK ON THE EXAM ONY (NO SCRATCH PAPER AOWED). READ THE QUESTION AND A ANSWERS CAREUY AND SEECT THE BEST ANSWER. A QUESTIONS ARE WEIGHTED EQUAY. () If a motor is turning a shaft with a torque of T ft-lb at a rate of n rpm, how much horsepower is being delivered? (a) πtn / 55 (b) 55πTn (c) πtn / 65 (d) 65πTn () If an axial force is specified in units of kn and the cross section area is specified in mm, what is the appropriate unit for axial stress? (a) mpa (b) Pa (c) kpa (d) MPa (e) GPa Questions 3 through 4 deal with the figure below: σ MAT MAT ε

2 (3) Which material has a higher yield strength? (a) MAT (b) MAT (4) Which material has a higher ultimate strength? (a) MAT (b) MAT Questions 5 through 8 deal with the curved rod of diameter d and inner radius of curvature r shown below. A d B r (5) The bending moment M used to calculate the bending stress at point A is (a) d (b) (d/) (c) r (d) (r + d/) (e) (r + d) (6) The r c ratio used to determine the K factors is (a) r / d (b) r / (d/) (c) (r + d) / (d/) (d) (r + d/) / d (e) (r + d/) / (d/) (7) The total normal stress at point B is calculated as (a) σ bending + σ axial (b) σ bending σ axial (c) σ axial σ bending (d) σ axial σ bending (8) How does the magnitude of the actual normal stress due to bending at point A compare with the magnitude that would be obtained using the straight beam equation? (a) it is larger (b) it is smaller (c) it is the same

3 Questions 9 through deal with the bar of length and diameter d shown below. The left end of the bar is fixed to a wall. The free end is loaded with two forces and a torque as shown. The stress magnitudes at the wall (not including signs for direction) will be referred to below using the following labels: A: maximum bending stress magnitude due to x B: maximum bending stress magnitude due to y C: maximum torsion shear stress magnitude due to T z D: maximum transverse shear stress magnitude due to x E: maximum transverse shear stress magnitude due to y Note: the points labeled "top" and "front" are on the outer surface of the part on the vertical and horizontal planes of symmetry of the cross section. top x front y (9) What is the value of "A: maximum bending stress magnitude due to x "? (a) 3 x / πd 3 (b) 64 x / πd 3 (c) 3 x / πd 4 (d) 6 x / πd 3 (e) 8 x / πd 4

4 () The total normal stress at the point labeled "front" is equal to (a) A (b) B (c) -A (d) -B (e) A - B () The magnitude of the total shear stress at the point labeled "top" is equal to (a) C (b) E + C (c) D + C (d) E - C (e) D - C () The transverse shear due to y is zero on the (a) top surface (b) front surface Questions 3 through 5 deal with the biaxial state of stress illustrated below where σ z =: (3) If σ x =, σ y = -, and τ xy =, the maximum shear stress in the material is (a) (b) 5 (c) 75 (d) (e) (4) If σ x =, σ y =, and τ xy = 5, the maximum shear stress in the material is (a) (b) 5 (c) 75 (d) (e)

5 (5) If σ x =, σ y = -, and τ xy = 5, which direction below corresponds to the smallest angle to the maximum principal stress? (a) clockwise from σ x (b) counterclockwise from σ x (c) clockwise from σ y (d) counterclockwise from σ y (6) If the plate below has a thickness t and a stress concentration factor of, what is the correct expression for the maximum normal stress at the hole? d w (a) / t(w - d) (b) / t(w - d) (c) / t(w - d/) (d) / t( - d) (e) / t( - d) Questions 7 through 9 deal with the beam shown below. oad is applied at the center of the beam. Refer to the vertical reaction force at the right support as R y. NOTE: x is measured from the right side of the beam. Neglect transverse shear effects. x (7) What is the correct expression for the bending moment M(x) for <x</ (using the positive bending moment sign convention)? (a) xr y (b) xr y - / (c) xr y + / (d) / (e) -/

6 (8) Which equation below is valid and can be used to help solve for the reaction force R y? (a) (b) (c) (d) (e) (9) Which expression below can be used to find the deflection at the center of the beam? (a) (b) (c) (d) () If M(x) = Px, what is (a) P (b) P (c) P / (d) P 3 (e) P 3 / M -- M dx P

7 Questions through 4 deal with applying Castigliano s Method to the frame below consisting of 3 segments. Do not neglect any elastic energy terms and include all existing elastic terms (even if the partial derivative terms are zero). 3 b M a () What is the reaction bending moment at the fixed end of section? (a) M + a (b) M + b (c) M - a (d) M - b (e) M () In finding the horizontal deflection of the free end of section 3, what energy terms need to be included for section? (a) none (b) transverse shear only (c) axial and bending only (d) transverse shear and bending only (e) axial, transverse shear, and bending (3) In finding the horizontal deflection of the free end of section 3, what energy terms need to be included for section? (a) none (b) axial only (c) bending only (d) axial and bending only (e) axial, transverse shear, and bending (4) In finding the vertical deflection of the free end of section 3, what energy terms need to be included for section 3? (a) none (b) transverse shear only (c) axial only (d) axial and transverse shear only (e) axial, transverse shear, and bending